DE102013103338A1 - Internal combustion engine - Google Patents

Abstract

The invention relates to an internal combustion engine, in particular an internal combustion engine with turbocharging for a motor vehicle, with at least one working cylinder, the working cylinder having a plurality of gas exchange valves, a first number of gas exchange valves being assigned to an intake side and a second number of gas exchange valves being assigned to an exhaust side. wherein a first camshaft is assigned to the gas exchange valves on the inlet side and a second camshaft is assigned to the gas exchange valves on the exhaust side, each camshaft having at least one cam which can be used to control the stroke of a gas exchange valve, at least one camshaft being a variable camshaft, which at least has a variable cam which has at least a first cam profile, a second cam profile and a third cam profile, the variable camshaft and / or the variable cam via an actuator or the like It is adjustable that the gas exchange valve is controlled either by the first cam profile, the second cam profile or the third cam profile.

Description

The invention relates to an internal combustion engine, in particular a turbocharged internal combustion engine for a motor vehicle, with at least one working cylinder, wherein the working cylinder has a plurality of gas exchange valves, wherein a first number of the gas exchange valves is assigned to an inlet side and a second number of gas exchange valves is assigned to an outlet side, wherein the inlet side gas exchange valves are associated with a first camshaft and the outlet side gas exchange valves are associated with a second camshaft, each camshaft having at least one cam usable to control the stroke of a gas exchange valve. Moreover, the invention relates to a method for operating this internal combustion engine.

As part of the so-called downsizing, which describes the reduction of the displacement of internal combustion engines with constant performance, charged internal combustion engines gain increasingly in importance. In particular, the use of exhaust gas turbochargers is becoming increasingly widespread.

Due to the principle, internal combustion engines with turbochargers have a time-delayed torque build-up. This time offset arises because the turbocharger is driven by the exhaust gas flowing out of the internal combustion engine. The time offset is also commonly known as turbo lag. The turbo lag occurs primarily during a transition from part load operation to full load operation.

In order to increase the comfort for the occupants by avoiding this turbo lag and at the same time to achieve a higher dynamics of the drive, different solutions are known in the prior art.

The DE 10 2006 014 965 A1 discloses, for example, an internal combustion engine, in particular a gasoline engine, with a camshaft which has at least one cam for controlling the gas exchange valves. This cam is adjustable relative to the camshaft and thus can vary the valve timing of its associated valve.

The DE 102 32 942 B4 discloses a method of controlling a turbocharged internal combustion engine to evenly dispense torque. Here, a variable camshaft adjustment is used to prevent or reduce the turbo lag, which allows adjustment of the valve overlap time of the inlet valve and exhaust valve. For this purpose, the relative position of the camshaft to the crankshaft can be changed by means of a camshaft adjusting device.

A disadvantage of the solutions according to the prior art is in particular that camshafts with cam relatively movable to the shaft are very expensive and the production is associated with great effort. A further disadvantage is that the adjustment of individual cams relative to the camshaft or the adjustment of the entire camshaft relative to the crankshaft is relatively slow.

Therefore, it is the object of the present invention to provide an internal combustion engine, which is optimized over the known from the prior art solutions. Furthermore, it is the object of the invention to provide a method for operating the internal combustion engine.

The object with regard to the internal combustion engine is achieved with the features of claim 1.

An embodiment of the invention relates to an internal combustion engine, in particular a turbocharged internal combustion engine for a motor vehicle, with at least one working cylinder, the working cylinder having a plurality of gas exchange valves, wherein a first number of the gas exchange valves is associated with an inlet side and a second number of gas exchange valves associated with an outlet side wherein the intake side gas exchange valves are associated with a first camshaft and the exhaust side exhaust valves are associated with a second camshaft, each camshaft having at least one cam usable to control the lift of a gas exchange valve, at least one camshaft being a variable camshaft, the at least one variable cam having at least a first cam profile, a second cam profile and a third cam profile, wherein the variable camshaft and / or the variable cam is adjustable by an actuator such that the control of the gas exchange valve is optionally carried out by the first cam profile, the second cam profile or the third cam profile.

The internal combustion engine may advantageously have a plurality of working cylinders, which are arranged such that in each case a plurality of working cylinders is associated with a camshaft. According to the invention may be provided a variable camshaft, or a non-variable camshaft. A variable camshaft here describes a camshaft which has at least one variable cam, wherein the variable cam has a plurality of cam profiles. The non-variable camshaft, also called the camshaft is designated, in contrast, on cam, each having only one cam profile.

The gas exchange valves can be operated in the case of a non-variable camshaft only by a cam with only one profile. In the case of a variable camshaft, the gas exchange valves can each be actuated by a cam with several cam profiles.

This is particularly advantageous since the individual cam profiles can be designed individually, as a result of which the internal combustion engine as a whole can be operated closer to the optimum.

The adjustment by the actuator can be made such that the cam is displaced relative to the camshaft, whereby in each case different cam profiles are brought into engagement with the gas exchange valves. Alternatively, the entire variable camshaft can be moved by the actuator.

Furthermore, it may be particularly advantageous if the non-variable camshaft and / or the variable camshaft is adjustable in its phase position relative to a crankshaft driving it via a camshaft adjustment.

About an adjustment of the camshaft, the phase angle of the camshaft can be varied relative to the crankshaft. As a result, the actuation time of the gas exchange valves can be varied. This is particularly advantageous since optimizations of the internal combustion engine can be achieved by adjusting the phase position.

Both the non-variable camshaft and the variable camshaft can be adjusted via a camshaft adjustment.

A preferred embodiment is characterized in that the first camshaft and / or the second camshaft is a variable camshaft.

Both the first camshaft associated with the intake side and the second camshaft associated with the exhaust side may be formed by a variable camshaft. In this way, both the inlet into the working cylinder and the outlet from the working cylinder can be influenced via variable cams.

This is advantageous for the most efficient operation of the internal combustion engine.

It is also preferable if the first camshaft is a variable camshaft and the working cylinder on the inlet side is preceded by a Helmholtz resonance intake system.

A Helmholtz resonance suction system is particularly advantageous due to their design to achieve the best possible filling of the working cylinder. A combination with a variable camshaft on the inlet side can further optimize the filling of the working cylinder. In particular, when the cam profiles of the variable camshaft are tuned to the use of a Helmholtz resonance intake system, the efficiency of the internal combustion engine can be optimized.

In a particularly favorable embodiment of the invention, it is also provided that the first cam profile of the variable camshaft, in comparison to a cam profile of a non-variable camshaft, causes a reduced stroke and a reduced opening duration of the respective gas exchange valve.

As a result, it can be achieved, for example, particularly advantageously that a high proportion of residual gas remains within the working cylinder. In particular, in a phase in which only a partial load is required by the internal combustion engine, this can be advantageous.

In an alternative embodiment of the invention, it can be provided that the second cam profile of the variable camshaft, compared to a cam profile of a non-variable camshaft causes a reduced lift of the respective gas exchange valve, wherein the stroke is greater than that caused by the first cam profile hub.

In this way, depending on the arrangement of the variable camshaft on the inlet side and / or the outlet side, a respectively optimal control of the gas exchange valves can be achieved. In particular, a low residual gas content and a high proportion of air mass in the working cylinder can be achieved.

Further, it is preferable if the third cam profile of the variable camshaft causes an accelerated gas exchange as compared with a cam profile of a non-variable camshaft.

The accelerated gas exchange is achieved by the highest possible overlap in the timing of the gas exchange valves. While the gas exchange valves open the inlet side, the gas exchange valves of the outlet side are still open, whereby a flushing of the working cylinder is made possible. Depending on the exhaust backpressure behind the outlet side and the boost pressure before the Inlet side, so a particularly optimal gas exchange in the working cylinder can be achieved.

According to a particularly preferred embodiment of the invention, it may be provided that the first and / or the second and / or the third cam profile is optimized so that in combination with an activated Helmholtz resonance suction system optimized filling of the working cylinder can be achieved.

In particular, the coordination of the second cam profile to an operation with an activated Helmholtz resonance intake system may be advantageous in order to achieve an optimized filling of the working cylinder. As a result, the internal combustion engine can be operated more efficiently.

Advantageously, in particular the second cam profile is tuned to the Helmholtz resonance intake system. But also a vote of the first and / or the third cam profile on the use of a Helmholtz resonance suction system may be advantageous.

The object with regard to the method is achieved with the features of claim 9.

An embodiment of the invention relates to a method for operating an internal combustion engine according to any one of the preceding claims, wherein a driving sequence, in particular a start-up sequence is traversed, which essentially divides into three phases, wherein in each of the phases, the gas exchange valves of the inlet side and / or In the first phase, the gas exchange valves which are actuated via a variable camshaft, are actuated via the first cam profile, in the second phase via the second cam profile and in the third phase via the third cam profile.

It is particularly advantageous if the different cam profiles are each designed for individual operating states of the internal combustion engine. This can be achieved in combination with a quick switchover between the individual cam profiles a very efficient operation of the internal combustion engine. In particular, the different requirements can be satisfied in partial load operation and full load operation.

A further preferred embodiment is characterized in that the three phases follow one another, wherein in the first phase a partial load is requested by the internal combustion engine, and in the second phase, a full load is requested by the internal combustion engine, wherein the boost pressure generated by the turbocharger is even lower , as the exhaust back pressure on the exhaust side, wherein in the third phase also a full load is requested, wherein the turbocharger boost pressure in the third phase increases, the boost pressure is always less than the exhaust back pressure or equal to the exhaust back pressure on the exhaust side.

The three successive phases result from the requirement of a full load from the internal combustion engine starting from a partial load operation. The cam profiles of the cam of the variable camshaft are adapted to the individual phases in order to ensure optimum operation of the internal combustion engine in each of the phases. This makes a particularly efficient operation possible.

It is also preferable if the first three phases of a fourth and / or a fifth phase follow, wherein in the fourth phase, the boost pressure generated by the turbocharger is greater than the exhaust gas back pressure on the outlet side. In the fifth phase, a stationary state can be achieved, wherein a partial load is requested by the internal combustion engine.

The driving sequence described above consists of four or five phases. The first three phases are followed by a fourth phase. In the fourth phase, the boost pressure exceeds the exhaust back pressure on the exhaust side. There is a purging of the working cylinder by a gas mixture is promoted from the inlet side with a boost pressure in the working cylinder, which is higher than the back pressure, which prevails on the outlet side through the exhaust gas.

The fourth phase may be followed by a fifth phase. In the fifth phase, the stationary target values are reached and again a partial load is requested from the internal combustion engine.

Advantageous developments of the present invention are described in the subclaims and the following description of the figures.

In the following the invention will be explained in detail by means of an embodiment with reference to the drawing. In the drawing show:

1 to 3 Valve lift curves for a configuration of an internal combustion engine, wherein the outlet side gas exchange valves is associated with a variable camshaft and the inlet side gas exchange valves is assigned a non-variable camshaft, said 1 a first phase depicts the 2 a second phase following the first phase and the 3 depicts a third phase following the second phase,

4 to 6 Ventilhubkurven for a configuration of an internal combustion engine, wherein the gas exchange valves the exhaust side is assigned a variable camshaft and the gas exchange valves of the inlet side is also associated with a variable camshaft, said 4 depicts a first phase, the 5 a second phase following the first phase and the 6 depicts a third phase following the second phase,

7 to 9 Valve lift curves for a configuration of an internal combustion engine, wherein the outlet side gas exchange valves associated with a non-variable camshaft and the inlet side gas exchange valves is assigned a variable camshaft, said 7 depicts a first phase, the 8th a second phase following the first phase and the 9 depicts a third phase following the second phase,

10 to 12 Ventilhubkurven for a configuration which provides a variable camshaft for the gas exchange valves on the inlet side, with a Helmholtz resonance intake system is also provided on the inlet side, and

13 to 15 Valve lift curves for a configuration which provides a non-variable camshaft for both the intake side gas exchange valves and the exhaust side gas exchange valves;

16 an arrangement of a Helmholtz resonance intake system on the inlet side of an internal combustion engine.

The 1 to 15 each show a diagram with a Ventilhubkurve for the valves of the exhaust side and a valve lift curve for the valves of the inlet side of a working cylinder.

Each of the diagrams represents a total of one crankshaft revolution, in which a piston is guided within the working cylinder from its bottom dead center UT to the top dead center OT and from this back to bottom dead center UT. The area shown in each case in the left part of the diagrams denotes the Ausschiebevorgang, in which the working gas is ejected from the working cylinder. The right-hand portion of the diagrams designates the intake phase of the internal combustion engine. In this intake phase, a fresh gas is sucked into the working cylinder or injected into a turbocharged engine in this.

Based on the timing, which are influenced by the camshafts on the inlet side and on the outlet side of the internal combustion engine, the proportion of fresh gas and the proportion of working gas in the working cylinder can be influenced. With the timing is on the one hand, the opening of the exhaust valve AÖ and the closing of the exhaust valve AS designated. On the inlet side, the timing is characterized by the opening of the inlet valve EÖ and the closing of the inlet valve ES.

As an additional variable, the maximum lift of the exhaust valve or intake valve is added. This is reached at the vertex of the valve lift curves. The larger the opening of the respective valve, the more gas can flow through it in a given time.

The 1 . 4 . 7 . 10 and 13 each describe the first phase in the operation of the internal combustion engine. In the first phase, a partial load is requested from the internal combustion engine. The turbocharger of the internal combustion engine is not or only to a very limited extent active.

The 2 . 5 . 8th . 11 and 14 denote the second phase in the operation of the internal combustion engine. In the second phase, a full load is requested from the internal combustion engine. The turbocharger is also not active during the second phase or only to a very limited extent. In principle, a boost pressure prevails in front of the working cylinder on the inlet side and an exhaust back pressure downstream of the working cylinder on the outlet side. Depending on the ratio of these two pressures to one another filling of the working cylinder is favored with fresh gas or a whereabouts of the working gas in the working cylinder.

In phase 2, the boost pressure is still significantly lower than the exhaust gas back pressure. Therefore, there is always a tendency in phase 2 for working gas to remain in the working cylinder and not completely replaced by an incoming fresh gas. This tendency can be enhanced or mitigated by adapted timing and special strokes of the exhaust or inlet valves.

The 3 . 6 . 9 . 12 and 15 show the operation of the internal combustion engine, in which also a full load is demanded and the boost pressure builds up steadily through the turbocharger until it agrees with the exhaust back pressure or even exceeds this after completion of the third phase.

This operating state of the internal combustion engine is designated phase 3. The higher the boost pressure caused by the turbocharger, the stronger the tendency that the working cylinder is completely filled with fresh gas, since the working gas in the working cylinder is pushed out of the working cylinder via the outlet side by the higher charge pressure on the inlet side. Also in Phase 3, the tendency for complete replacement of the working gas with fresh gas also depends on the timing of the exhaust valves and intake valves and the lift of the exhaust and intake valves.

Working gas, which remains after passing through top dead center in the working cylinder, is referred to as residual gas.

The 1 to 3 show a configuration of the internal combustion engine, wherein the inlet side of a non-variable camshaft and the outlet side has a variable camshaft. The exhaust valves are accordingly actuated in phase 1 with the first cam profile, in phase 2 with the second cam profile and in phase 3 with the third cam profile of the variable camshaft. During all three phases, the intake valves are always actuated via the non-variable cam profile of the non-variable camshaft.

The 1 shows a valve lift curve 1 an exhaust valve. It is characterized by a late closing of the exhaust valve AS. The closing of the exhaust valve AS takes place clearly after top dead center.

The valve lift curve 2 of the inlet valve is shown in the right part of the diagram. The inlet valve opens EÖ at top dead center OT and closes significantly after bottom dead center UT. Due to the late closing of the outlet valve AS and the pressure conditions prevailing in phase 1 at the inlet and outlet sides, a high proportion of residual gas remains in the working cylinder. In addition, the lift of the exhaust valve in phase 1 is lower than it would be with a non-variable camshaft. This also favors the whereabouts of a high proportion of residual gas in the working cylinder. In addition, the opening of the exhaust valve AÖ immediately after the bottom dead center promotes a higher expansion work on the piston of the working cylinder.

In phase 2, the timing for opening the exhaust valve AÖ is earlier than in phase 1. This is at the valve lift curve 3 to recognize. The closing of the exhaust valve AS is earlier, namely already shortly after the top dead center TDC. The valve lift curve 4 refers to the intake valves. The inlet valve opens EÖ slightly earlier, namely shortly before the top dead center OT and closes significantly after the bottom dead center UT. The stroke of the exhaust valve is also greater than in phase 1. The larger stroke and the earlier closing of the exhaust valve AS combined with the pressure ratios on the outlet side and the inlet side ensures that only a small proportion of residual gas remains in the working cylinder.

In 3 Phase 3 is shown. The left side of the diagram shows the valve lift curve 5 the movement of the exhaust valve. This is characterized by a particularly early opening of the exhaust valve AÖ before bottom dead center UT and a particularly late closure of the exhaust valve AS after top dead center OT.

The valve lift curve 6 in the right part of the diagram shows the movement of the inlet valve. The inlet valve EÖ opens significantly before the top dead center OT. The inlet valve closes ES after bottom dead center UT. However, the closing of the intake valve ES takes place somewhat earlier than in phases 1 and 2.

In phase 3, the overlap between the still open exhaust valve and the already open intake valve is greatest. However, due to the prevailing at the inlet side and the outlet pressure conditions, there is still no complete flushing of the working cylinder. There remains a residual gas content within the working cylinder.

With purging, a process is described in which it comes through the overlap of the opening of the exhaust valve and the intake valve to an almost complete expulsion of the working gas from the working cylinder in the exhaust system. In this case, fresh gas can flow through the working cylinder into the exhaust system.

As a result, the filling of the working cylinder can be substantially improved with fresh gas.

The stroke of the exhaust valve is significantly increased compared to the phases 1 and 2 and is at the level of the stroke of the intake valve, which is actuated by a non-variable camshaft.

By opening the intake valve EÖ before the top dead center OT and the closing of the exhaust valve AS only after the top dead center OT in the last phase of the Ausschiebevorgangs working gas is pushed into both the inlet tract and in the outlet tract. When the piston is reversed at top dead center OT, part of the working gas that has just been ejected is then sucked back into the working cylinder through the open exhaust valve and the opened inlet valve, resulting in a proportion of residual gas in the working cylinder. By a boost pressure that is greater than the exhaust back pressure is, the proportion of residual gas remaining in the cylinder, can be further reduced.

The 4 to 6 show an embodiment in which a variable camshaft is provided on both the exhaust side and on the inlet side.

Phase 1 stands out in 4 by opening the exhaust valve AÖ at bottom dead center UT and closing the exhaust valve AS immediately after the top dead center OT. This shows the valve lift curve 7 , The valve lift curve 8th shows the movement of the intake valve. The inlet valve EÖ opens significantly before the top dead center OT and ES closes significantly before reaching the bottom dead center UT.

Due to the relatively low valve lift both on the exhaust side and on the inlet side and the overlap of the exhaust valve and the inlet valve remains in phase 1 of the 4 a high proportion of residual gas within the working cylinder.

Phase 2 in 5 is characterized by an early opening of the exhaust valve AÖ directly before the bottom dead center UT. The exhaust valve closes AS immediately after reaching top dead center OT. The movement of the exhaust valve is through the valve lift curve 9 shown. The inlet valve opens EÖ immediately before reaching top dead center OT and closes ES shortly after reaching the next bottom dead center UT. The valve lift curve 10 shows this.

Between the exhaust valve and the inlet valve is in 5 as good as no overlap. A backflow of already expelled working gas from the outlet side is not possible or only to a very limited extent by the closing of the outlet valve AS immediately after top dead center OT.

Due to the late opening of the inlet valve EÖ no working gas has been ejected into the inlet area. Therefore, results for the working cylinder a filling with a very low residual gas content and a very high proportion of fresh gas. The stroke of both the exhaust valve and the intake valve is lower than that of a comparable non-variable camshaft. At the same time, the timing at which the intake valve closes ES earlier than with a non-variable camshaft. Thus, less charge is lost by pushing back into the inlet channel.

The phase 3 in 6 is characterized by an early opening of the exhaust valve AÖ before the bottom dead center UT. The exhaust valve closes AS significantly after top dead center OT. At the same time, the inlet valve EÖ opens significantly before the top dead center OT and closes ES after reaching the next bottom dead center UT. Thus, there is a large overlap between the exhaust valve and the intake valve. The movement of the exhaust valve is via the valve lift curve 11 and the movement of the intake valve is above the valve lift curve 12 shown.

Since the charge pressure on the inlet side increases, but is still lower than the exhaust gas back pressure on the exhaust side, the delivery rate of the working cylinder is relatively low. Due to the overlap of the exhaust valve and the inlet valve, a residual gas content remains in the working cylinder.

The 7 to 9 show an embodiment with a non-variable camshaft on the exhaust side and a variable camshaft on the inlet side.

In phase 1 opens the outlet valve AÖ well before the bottom dead center UT. It closes AS only after reaching top dead center OT. This is in the valve lift curve 13 shown. The inlet valve opens EÖ clearly before the top dead center OT and already closes ES significantly before reaching the bottom dead center UT. Overall, the inlet valve has a shortened opening duration. The valve lift curve 14 represents the movement of the intake valve. The intake valve closes ES at approximately halfway of the piston between top dead center OT and bottom dead center UT.

Furthermore, the lift of the intake valve is relatively low. Due to the overlap between the outlet valve and inlet valve, a large proportion of residual gas remains within the working cylinder.

The 8th shows the second phase, which is marked by an early opening of the exhaust valve AÖ well before the bottom dead center UT and a closing of the exhaust valve AS clearly after the top dead center OT. The valve lift curve 15 shows this. At the same time, the inlet side is characterized in that the inlet valve opens immediately before the top dead center OT EÖ and only after reaching the next bottom dead center UT again closes ES. This shows the valve lift curve 16 ,

By opening only immediately before the top dead center OT, the proportion of the residual gas in the working cylinder can be kept low, while the proportion of fresh gas is significantly increased.

In phase 3, a maximum overlap is provided between the exhaust valve and the intake valve. The inlet valve opens EÖ clearly before the top dead center OT, the exhaust valve only after the top dead center TDC closes AS. As a result, and by the prevailing on the inlet side and the outlet pressure conditions, the delivery rate is still relatively low. The outlet opens AÖ before the first bottom dead center UT, the inlet ES closes after the subsequent bottom dead center UT.

The stroke of the intake valves and the lift of the exhaust valves is approximately equal. In particular, the lift of the intake valves is significantly increased compared to the stroke in phases 1 and 2. The movement of the exhaust valve is through the valve lift curve 17 , the movement of the intake valve is through the valve lift curve 18 shown.

There is a large overlap between the exhaust valve and the intake valve. Therefore, a residual gas content remains in the working cylinder.

The 10 to 12 show a configuration which is characterized both by a variable camshaft on the valves of the inlet side and by an inlet side Helmholtz resonance suction system. The exhaust side valves are actuated by a non-variable camshaft.

10 shows the first phase. In this case, a very early opening AÖ of the exhaust valve is shown clearly before bottom dead center UT. The exhaust valve closes AS shortly after reaching top dead center OT. This is in the valve lift curve 50 shown. The inlet valve opens EÖ well before the top dead center and closes ES significantly before reaching the bottom dead center UT. The piston has traveled at this time about three quarters of the way from top dead center OT to bottom dead center UT. The lift of the intake valve is significantly reduced compared to a configuration without a variable camshaft. The valve lift curve of the intake valve is denoted by the reference numeral 51 characterized.

11 shows the second phase. The exhaust valve is characterized by a very early opening AÖ before the bottom dead center UT. The exhaust valve closes AS after reaching top dead center OT. The Ventilhubkurve the outlet side is denoted by the reference numeral 52 named. The inlet valve opens EÖ shortly before reaching top dead center OT and closes ES again shortly after reaching bottom dead center UT. The lift of the intake valves is also reduced compared to intake valves not driven by a variable camshaft. The Ventilhubkurve the inlet side is denoted by the reference numeral 53 characterized.

12 shows phase 3 of the configuration. The valve lift curve 54 shows an opening of the exhaust valve AÖ before bottom dead center UT and closing AS after top dead center. The inlet valve opens EÖ in turn already before the top dead center OT and closes only after the bottom dead center UT. There is a relatively large overlap between the exhaust valve and the intake valve. The lift of both the exhaust valve and the intake valve is approximately at the level of a non-variable camshaft configuration for the intake side and the exhaust side.

To the respective phases 3 of the 3 . 6 . 9 and 12 This is followed by another phase in which the boost pressure due to the turbocharger now clearly exceeds the exhaust back pressure behind the working cylinder.

As a result, the working cylinder is flushed out, which means that the working gas in the working cylinder is almost completely blown out of the working cylinder via the outlet side. This is done by blowing the fresh gas into the working cylinder. The working cylinder can be almost completely filled with fresh gas, whereby a better combustion can be generated and thus creates an optimized power delivery.

The configuration of 1 to 3 As a result, the third phase ends earlier than it would with an internal combustion engine with two non-variable camshafts. The configuration of 4 to 6 causes phase 3 to complete even earlier than the configuration of 1 to 3 , The configuration of 7 to 9 This means that Phase 3 is completed faster than would be the case with an internal combustion engine with two non-variable camshafts, but lasts longer than the configuration of the engine 4 to 6 , The configuration of 10 to 12 with regard to the termination of phase 3 correspond to the ratios of 7 to 9 , The timing is unchanged. Only the filling of the working cylinder is improved due to the Helmholtz resonance intake system installed on the inlet side.

Overall, it should be noted that a high variability can be achieved by an embodiment of an internal combustion engine with a variable camshaft both on the inlet side and on the outlet side. Both the valves of the inlet side and the valves of the outlet side can be adapted to the respective operating state. The two variable camshaft configuration is the most advantageous embodiment.

The 13 to 15 show a configuration in which non-variable camshafts are provided on both the intake side and the exhaust side. They represent part of the state of the art.

The valve lift curves for the conventional embodiment are for the phase 1 by the reference numerals 19 and 20 for the exhaust valve or the intake valve. For phase 2, the valve lift curve of the exhaust valve is designated by the reference numeral 21 and the valve lift curve of the intake valve by the reference numeral 22 marked. In phase 3, the valve lift curve of the exhaust valve with 23 and the valve lift curve of the intake valve with 24 labeled.

By comparing the 1 to 1 with the 13 to 15 In particular, it can be seen how the timing of the individual configurations differ from each other and how the strokes of the intake and exhaust valves differ from one another in the individual configurations.

The in the 1 to 15 shown curves for the valve lift curves are exemplary and have no limiting character. They serve only to clarify the principle of the invention.

The respective control times for the opening of the exhaust valve AÖ, the closing of the exhaust valve AS, the opening of the inlet valve EÖ and the closing of the inlet valve ES of the figures shown each relate to a specific design and structural design of the overall system. By changing the mechanical parameters, such as the cam profiles, or changing the control parameters, a large change in the curves shown in the figures can be achieved. The detailed description of the exemplary courses of the FIGURE serves to illustrate the overall context and an explanation of the variables that can be changed in each case. The courses shown in the figures do not represent any limitations to possible solutions which follow the inventive concept.

The opening of the exhaust valve AE can be done in an alternative embodiment before reaching the bottom dead center UT, upon reaching the bottom dead center UT or after reaching the bottom dead center. Likewise, in an alternative embodiment, the closing of the exhaust valve AS before reaching the top dead center OT, when reaching the top dead center OT or after reaching the top dead center.

The opening of the intake valve EÖ can be done in an alternative embodiment before reaching the top dead center OT, upon reaching the top dead center OT or after reaching the top dead center. The closing of the inlet valve ES can be done in an alternative embodiment before reaching the bottom dead center UT, upon reaching the bottom dead center UT or after reaching the bottom dead center UT.

The alternative embodiments described above can be combined with each other.

The 16 shows a schematic view of a cylinder bank 35 an internal combustion engine with a working cylinders upstream Helmholtz resonance suction system 31 , About the arrangement of one or more air volumes 32 . 33 at the intake tract 38 the internal combustion engine, can advantageous oscillations of the air in the intake system 38 can be achieved, leading to improved filling of the working cylinder with fresh gas. The air volume 32 . 33 stand for it with the intake tract 38 over the connecting pipes 33 . 34 in fluid communication. About the flaps 40 . 41 can the connecting pipes 33 . 34 partially or completely closed.

The two air volumes 32 . 33 are over a single flap 42 separated from each other. Depending on the position of the flap 42 can the air volume 32 . 33 be connected with each other.

The fresh gas flows along the arrow 37 in the intake tract 38 one. This influx is over the flap 39 influenced. The intake tract 38 stands with the individual working cylinders of the cylinder bank 35 via one pipe each 36 in fluid communication.

The operating principle of the Helmholtz resonance suction system 31 is based on overlaying unfavorable vibrations with a phase-shifted oscillation in order to reduce or completely eliminate the effects of the unfavorable oscillation.

In addition to an optimized filling of the working cylinder is also a reduction of disturbing noises on a Helmholtz resonance suction system 31 possible.

The Helmholtz resonance intake system 31 , is advantageously activated after the end of phase 1. These are the flaps 40 . 41 . 42 switched so that they allow optimal filling of the working cylinder with fresh gas.

This activation of the Helmholtz resonance intake system 31 is assisted by switching the variable camshaft to the second cam profile. By shifting the time, In which the inlet valve opens EÖ backwards, the excitation by the piston and thus the pressure amplitude is amplified. In addition, the phase position of the resonance oscillation with the closing of the inlet valve ES is optimally tuned by the second cam profile. This vote of the second cam profile on the resonant vibrations in the system can be speed-dependent.

By optimizing the individual sizes, the amount of air required, ie the amount of air supplied to the working cylinder, can be significantly increased. A higher air expenditure in turn leads to a faster buildup of the boost pressure through the turbocharger, whereby the time delay is reduced to the response of the turbocharger.

The in the 16 shown embodiment of a Helmholtz resonance suction system is exemplary and has no limiting character. Both the number and the arrangement of the individual air volumes is variable, as well as the interconnection of the air volume with each other via the flaps.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006014965 A1 [0005]
• DE 10232942 B4 [0006]

Claims (11)

Internal combustion engine, in particular a turbocharged internal combustion engine for a motor vehicle, with at least one working cylinder, wherein the working cylinder has a plurality of gas exchange valves, wherein a first number of the gas exchange valves is associated with an inlet side and a second number of the gas exchange valves is associated with an outlet side, wherein the gas exchange valves of the Each camshaft has at least one cam, which is used to control the stroke of a gas exchange valve, characterized in that at least one camshaft is a variable camshaft, the at least one variable cam having at least a first cam profile, a second cam profile and a third cam profile, wherein the variable camshaft and / or the variable cam via an actuator such ve can be set that the control of the gas exchange valve is made either by the first cam profile, the second cam profile or the third cam profile. Internal combustion engine according to claim 1, characterized in that the non-variable camshaft and / or the variable camshaft is adjustable in its phase position relative to a crankshaft driving it via a camshaft adjustment. Internal combustion engine according to one of the preceding claims, characterized in that the first camshaft and / or the second camshaft is a variable camshaft. Internal combustion engine according to one of the preceding claims, characterized in that the first camshaft is a variable camshaft and the working cylinder on the inlet side a Helmholtz resonance suction system ( 31 ) is connected upstream. Internal combustion engine according to one of the preceding claims, characterized in that the first cam profile of the variable camshaft, compared to a cam profile of a non-variable camshaft, causes a reduced stroke and a reduced opening duration of the respective gas exchange valve. Internal combustion engine according to one of the preceding claims, characterized in that the second cam profile of the variable camshaft, compared to a cam profile of a non-variable camshaft causes a reduced lift of the respective gas exchange valve, wherein the stroke is greater than the stroke caused by the first cam profile stroke. Internal combustion engine according to one of the preceding claims, characterized in that the third cam profile of the variable camshaft, as compared to a cam profile of a non-variable camshaft, causes an accelerated gas exchange. Internal combustion engine according to claim 4, characterized in that the first and / or the second and / or the third cam profile is optimized in such a way that in combination with an activated Helmholtz resonance intake system ( 31 ) an optimized filling of the working cylinder is reached. Method for operating an internal combustion engine according to one of the preceding claims, characterized in that a driving sequence, in particular a start-up sequence, is traversed, which essentially divides into three phases, wherein in each of the phases the gas exchange valves of the inlet side and / or the gas exchange valves of the outlet side operated by a variable camshaft, wherein in the first phase, the gas exchange valves which are actuated via a variable camshaft, are actuated via the first cam profile, in the second phase via the second cam profile and in the third phase via the third cam profile. A method of operating an internal combustion engine according to claim 9, characterized in that the three phases follow one another, wherein in the first phase a partial load from the internal combustion engine is requested, and in the second phase, a full load is requested by the internal combustion engine, which is generated by the turbocharger Charge pressure is still lower than the exhaust back pressure on the exhaust side, and in the third phase also a full load is requested, wherein the turbocharger boost pressure already increases, the boost pressure is always less than the exhaust back pressure or equal to the exhaust back pressure on the exhaust side. Method for operating an internal combustion engine according to any one of the preceding claims 9 or 10, characterized in that adjoins the first three phases of a fourth and / or a fifth phase, wherein in the fourth phase, the boost pressure generated by the turbocharger is greater than the exhaust back pressure on the exhaust side and wherein in the fifth phase, a steady state is reached and a partial load is requested by the internal combustion engine.

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